Artificial Intelligence (CS F407) Machine Learning: Introduction Chittaranjan Hota Professor, Computer Science & Information Systems Department BITS Pilani Hyderabad Campus, Hyderabad hota@hyderabad.bits-pilani.ac.in Some tasks… Content Promotion, Content Price Modeling, Adaptive Streaming QoE… ‘cocktail party problem’ What is Learning? “Learning denotes changes in a system that enables a system to do the same task more efficiently the next time.” – Herbert Simon (Writing your AI Midsem and then Compre…) Learning is the process of acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences- Wiki Humans learn from experiences…. h1 , h2 ,..., hK … xN System y1 y2 yM Hidden Variables: data data program output program output Output Variables x1 x2 … Input Variables What is Machine Learning? Defining the Learning Task Improve on task, T, with respect to performance metric, P, based on experience, E (Tom Mitchell, 1997). T: Playing chess P: Percentage of games won against an arbitrary opponent E: Playing practice games against whom? T: Recognizing hand-written words P: Percentage of words correctly classified E: Database of human-labeled images of handwritten words T: Categorize email messages as spam or legitimate. P: Percentage of email messages correctly classified. E: Database of emails, some with human-given labels Why Machine Learning is important? Machine learning is programming computers to optimize a performance criterion using example data. There is no need to “learn” to calculate payroll Learning is used when: Human expertise does not exist x: Bond graph for a new molecule, f(x): Predicted binding strength to AIDS protease molecule. Navigating on Mars Humans are unable to explain their expertise x: Bitmap picture of hand-written character, f(x): Ascii code of the character Speech recognition Continued… Solution changes in time x: Description of stock prices and trades